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In biology, a '''species''' (abbreviated '''sp.''', with the plural form '''species''' abbreviated '''spp.''') is one of the basic units of biological classification and a taxonomic rank. A species is often defined as the largest group of organisms in which two individuals are capable of reproduction|reproducing fertile offspring, typically using sexual reproduction. While in many cases this definition is adequate, the difficulty of defining species is known as the species problem. For example, a species complex is a group of closely related species that are very similar in appearance to the point that the boundaries between them are often unclear. Differentiating measures include similarity of DNA, morphology (biology)|morphology, or ecological niche. Presence of specific locally adapted traits may further subdivide species into "infraspecific taxa" such as subspecies (and in...
Volume6 | pages = 544–547 | issue=4 | pmid=20106856 | pmc=2936204}}{{Open access}} Extinct species known only from fossils are generally difficult to assign precise taxonomic rankings, which is why higher taxonomic levels such as families are often used for fossil-based studies.{{cite journal | url=http://rspb.royalsocietypublishing.org/content/275/1636/759 |author1=Sahney, S. |author2=Benton, M.J. |lastauthoramp=yes | year=2008 | title=Recovery from the most profound mass extinction of all time | journal=Proceedings of the Royal Society: Biological | doi=10.1098/rspb.2007.1370 | volume = 275 |format=PDF | pmid=18198148 | issue=1636 | pmc=2596898 | pages=759–65}}{{Open access}}
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RESULTS

COLLECTION
TOPIC atoz
Plants 2
Botany 1
DIY 1
Death 1
Flesh 1
Groove 1
Legion 1
Metal 1
Mosses 1
RedSK 1
Torn 1
USA 1
gaza 1
glitch 1
idm 1
noise 1
CREATOR
SHOW DETAILS
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